Postflop: What's our plan if either of the fish call our donk (I'm assuming we donk to isolate either of them)?

As played CO's range looks like PPs, draws and possibly some slowplays (our donk 4 way looks strong) so ck/folding turn is fine. With more history (if we can expect him to float lighter) we can bet/fold or ck/call but without info ck/fold is fine.